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Solar system lesson 1 11 trang

Solar
System
Lesson 1

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The Solar
System
Lesson 1

Lesson 1
What Is the Sun? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

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1
VOCABULARY
star


sun
fusion

What Is
the Sun?

A star looks like a point of light in the night sky.
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The sun is the large star. We can see it
during the day.

Most of the sun’s energy comes from
fusion. Two hydrogen atoms fuse and
make a helium atom.
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READING FOCUS SKILL

MAIN IDEA AND DETAILS
The main idea is what the text is mostly about.
Details are pieces of information about the main idea.
Look for details about the sun and how it produces
energy.

Stars
A star is a huge ball of very hot gases. The sun is the star at
the center of our solar system. From Earth, the sun looks like a
large ball of light.
The sun is the source of most energy on Earth. Without the
sun, life on Earth could not exist.
Scientists classify stars by size, temperature, and color. The
sun is an average size star. It is the largest body in the solar
system. The sun has a medium temperature.

Tell one detail about the sun.

The sun is a huge
ball of gases.

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Features of the Sun
The sun has several layers. At the center of the sun is the
core. Most of the sun’s mass is in the core. The other layers are
the radiation zone, the convection zone, and the photosphere.
The photosphere is the surface of the sun. Above the
photosphere is the sun’s atmosphere.

Name one layer of the sun.

The photosphere is the
surface of the sun.

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Fusion occurs in the
sun’s core.

How the Sun Produces Energy
Like other stars, the sun is made up of gases. These gases are
mostly hydrogen and helium. The sun’s energy comes from
fusion. Fusion is the joining of small particles into larger ones.
The temperature at the center of the sun is about
15 million ºC (27 million ºF). Under pressure, hydrogen
atoms smash into each other. This produces helium and
energy. The sun releases the energy as light and heat.

What is the temperature at the center of the sun?

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Core

Radiation Zone

Convection Zone

Photosphere

Review
Complete this main idea statement.
1. The ______ is the star at the center of our solar
system.

Complete these detail statements.
2. The sun is made up of gases, mostly ______ and
______ .
3. The sun releases ______ as light and heat.
4. The sun’s energy comes from ______ . That is the
combining of small particles into larger ones.

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GLOSSARY
fusion [FYOO•zhuhn] The energy-producing reaction that
occurs inside stars.
star [STAR] A huge ball of very hot gases in space.
sun [SUHN] The star at the center of the solar system.

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Think About the Reading
1. What can you do to help you remember what you have learned
about the sun?
2. What questions do you have after reading this book? How can
you find the answers to your questions?

Hands-On Activity
Make a work of art showing the sun and stars. You can show the color
range of stars. Show that many stars are visible in the night sky.

School-Home Connection
Explain to a family member what you have read about the sun. Ask a
family member to describe the size of the sun in the sky at noon and of
stars at sunset.

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